OVERVIEW OF PURPOSE, STAFFING, AND AIMS The overall purpose of the Yale ACE Assessment Core (AC) is to ensure that all projects have access to well-characterized patients, family members and control populations, from both a behavioral/phenotypic standpoint and from a medical/pediatric and genetics standpoint. By centralizing assessment procedures and ensuring consistency across projects, the efforts of this core also significantly contribute to the coherence of the Yale ACE and the mutually enriching synergy of the five component areas. In contrast to the assessment cores in the Yale CPEA and STAART, we address more extensively two critical issues inherent in complex research projects: (1) logistical and operational aspects of program implementation and (2) organizational, conceptual, and data management synergy within this program and collaboration with other scientific efforts within the Child Study Center and with those under the auspices of NIH networks of autism research. Our goal is to maximize scientific yield while responding to the critical need for centralized data bases through the National Database for Autism Research. The AC will be directed by Dr. Ami Klin, an experienced clinical researcher with expertise in behavioral characterization of individuals with autism spectrum disorders. The Core will be co-directed by Dr. Matthew State, a child psychiatrist and geneticist whose research focuses on gene discovery in developmental neuropsychiatric disorders. He will take responsibility for genetics lab work conducted within the scope of this. Dr. State is a longstanding collaborator of Drs. Klin, Volkmar, and Schultz. Other leading clinicians are Drs. Kasia Chawarska, Rhea Paul, and Celine Saulnier. Dr. Chawarska is an infancy specialist and seasoned clinical researcher who leads our clinics for infants and toddlers. Prior to completing her PhD, Dr. Chawarska had assessed many hundreds of infants in various research contexts (e.g., working with Dr. Linda Mayes at the Yale Child Study Center, Child Development Unit). For the past 6 years, Dr. Chawarska has led the evaluation of several hundred infants and toddlers with autism spectrum disorders (ASD) and other developmental disabilities. Dr. Rhea Paul is one of the leading speech-language pathologists in the country and a professor of Communication Disorders. Her experience in the field dates back to her work with Drs. Donald Cohen and Fred Volkmar in the early 1980's. She is the author of the main textbook in communication disorders and a contributor to the American Speech-Language-Hearing Association documents on best practice parameters in communication assessment of children with ASD. Dr. Saulnier is a neuropsychologist trained with Dr. Deborah Fein who was recruited through a NAAR mentorshipbased award (Dr. Klin, PI). She is now a leading clinician in our team and is a collaborator in research (e.g., Klin et al., In press;Saulnier &Klin, In press). All leading personnel in the AC work daily together in both clinical and research activities. The Core begins with several advantages: (1) the infrastructure for the AC, including clinical expertise, procedures, and management, has already been tested and proven in several past and ongoing program projects. Examples are: the Assessment Core for an NICHD-funded program project that ended in 2006 (Dr. Klin worked closely with Dr. Sara Sparrow, Core Director, for close to 15 years and, upon her retirement, replaced her as the Yale Child Study Center Chief of Psychology in 2002);the Assessment Core of the NICHD-funded program project that followed it (PO1 HD003008 38;Dr. Klin is Core Director, Dr. State is Core Co-Director);the Assessment Core of the NICHD-funded Collaborative Projects of Excellence in Autism (CPEA) (Dr. Klin was Co-Director of the Core, working closely with Dr. Catherine Lord, Core Director);and the Assessment Core of the NIMH-funded Yale STAART (Dr. Klin is Core Director, working closely with Drs. Paul and Chawarska, Core Associate Directors);(2) Dr. Klin, as reflected in longstanding collaborations with Drs. Volkmar, Sparrow, and Lord, has a longstanding interest in diagnostic issues, instrumentation and procedures, including development of new methods, training and education, and clinical assessment;(3) Drs. Klin, Paul, and Chawarska share a longstanding interest in assessment of infants and toddlers, have published novel research and didactic chapters pertaining to behavioral and experimental characterization of infants and toddlers with autism, and have evaluated several hundred children in this age bracket);and (4) The proposed functional expansion and refinement of the AC related to our information technology infrastructure has already been implemented in the context of one complex research program (a multivisit prospective study of siblings of children with autism from birth in PO1 HD003008 38). We prioritized that study because of its demanding and complex logistical challenges (primarily because of the multiple-visit nature of subject and family longitudinal participation in research and the need to minimize attrition and the loss of data points). Given that 4 of the 5 projects in this application involve infants in the second year of life, the similarities in measures and data formatting will allow for a quick expansion of the IT system to encompass most of the Yale ACE. The remaining project (Project IV) will follow. Its implementation will be relatively straightforward since subjects are already in the system (this is a cohort that has been followed-up since the age of 2 years) and the characterization protocol duplicates diagnostic and developmental measures used in other projects focused on school-aged children. We emphasize that this is not simply a proof of concept. Instead, this is a sophisticated information technology structure developed through the intimate collaboration with Prometheus Research for the past 1 Vz years. These various resources and connections are a reflection of the constant, intensive, and multifaceted web of collaborations bringing together the various leading investigators in the Yale ACE.